Human hair is nowadays treated in diverse ways with hair-cosmetic preparations. This includes, for example, the cleaning of the hair with shampoos, the care and regeneration with rinses and treatments, and also the bleaching, coloring and shaping of the hair using colorants, tints, waving compositions and styling preparations. In this connection, compositions for changing or nuancing the color of the head of hair play a prominent role. Disregarding the bleaching compositions which bring about an oxidative lightening of the hair as a result of degradation of the natural hair dyes, then essentially three types of hair colorants are of importance in the field of hair coloring:
For permanent, intensive colorations with corresponding fastness properties, so-called oxidation colorants are used. Such colorants usually comprise oxidation dye precursors, so-called developer components and coupler components. The developer components form the actual dyes under the influence of oxidizing agents or of atmospheric oxygen with one another or with coupling with one or more coupler components. Although the oxidation colorants are characterized by excellent, long-lasting coloring results, for colorations which look natural, it is usually necessary to use a mixture of a relatively large number of oxidation dye precursors; in many cases, direct dyes are also used for the nuancing. If the dyes formed during the course of the color development or used directly have considerably different fastnesses (e.g. UV stability, perspiration fastness, washfastness etc.), then over time a noticeable and therefore undesired color shift may result.
This phenomenon arises to a greater extent if the hair style has hair or zones of hair with differing degrees of damage. One example of this is long hair in which the tips of the hair, subjected for a long time to all possible environmental influences are usually damaged to a markedly greater degree than the relatively freshly grown zones of hair.
For temporary colorations, colorants or tints are usually used which comprise so-called substantives as coloring component. These are dye molecules which attach directly to the hair and require no oxidative process for developing the color. These dyes include, for example, henna which has already been known for a long time for coloring bodies and hair. These colorations are generally considerably more sensitive to shampooing than the oxidative colorations, meaning that an often undesired nuance shift or even a visible “decoloration” arises very much more quickly.
Finally, a new type of coloring method has recently received great attention. In this method, precursors of the natural hair dye melanin are applied to the hair; then, in the course of oxidative processes within the hair, these form nature-analogous dyes. One such method with 5,6-dihydroxyindoline as dye precursor has been described in EP-B1-530 229. In the case of use, in particular repeated use, of compositions containing 5,6-dihydroxyindoline, it is possible to restore the natural hair color in people with gray hair. The development of color can take place here with atmospheric oxygen as the sole oxidizing agent, meaning that recourse does not have to be made to any other oxidizing agent. For people with originally mid-blonde to brown hair, the indoline may be used as the sole dye precursor. For use for people with originally red and, in particular, darker to black hair color, by contrast, satisfactory results can often only be achieved through the co-use of further dye components, in particular special oxidative dye precursors. Here too, problems with regard to fastness of the colorations can arise.
There has been no lack of attempts to improve the fastness of colorations of keratin fibers. One development direction is the optimization of the dyes themselves or the synthesis of new, modified dye molecules. A further development direction is the search for additives for the colorants in order to increase the fastness of the colorations. A known solution to the problem is to add UV filters to the colorant. These filter substances are applied to the hair in the coloring process together with the dye, as a result of which, in many cases, a significant increase in the stability of the coloration toward the action of daylight or artificial light is achieved.
EP 0 655 905 B1 discloses the use of alkyl glycosides in colorants. DE-A 199 190 89 describes hair-coloring preparations containing sugar surfactants and fatty acid partial glycerides which strengthen the hair structure and are readily dermatologically compatible. However, no information with regard to color intensification and with regard to washfastness is disclosed.
Surprisingly, it has now been found that the use of the active ingredient combination according to the invention consisting of sugar surfactants and fatty acid partial glycerides, it is possible to significantly increase the washfastness and the color intensification of colorings, in particular of keratin fibers. For the purposes of the invention, washfastness is understood as meaning the retention of the original coloration with regard to nuance and/or intensity when the keratin fiber is subjected to the repeated influence of aqueous compositions, in particular surfactant-containing compositions such as shampoos. For the purposes of the invention, color intensification is understood as meaning that the coloration significantly increases in color strength as a result of application of the active ingredient combination according to the invention.